Dental matrix-retainer.



no MODEL.

PATENTED FEB. s, 1903.

MILLS. DENTAL MATRIX RETAINER.

AYPLIOATION III-IE1 SEPT. 6, 1902.

' tending to force the inner ends together, and

! NITED STATES PATENT OFFICE.

JOHN MILLS, OF BRANTFORD, CANADA.

DENTAL MATRIX-RETAINER.

SPECIFICATION forming part of Letters Patent No. 719,834, dated February 3, 1903.

Application filed September 5, 1902. Serial No. 122,236. (No model.)

To all whom it may concern.-

Be it known that I, JOHN MILLS, L. D. S., of the city of Brantford, in the county of Brant and Province of Ontario, Canada, have invented certain new and useful Improvements in Dental Matrix-Retainers, of which the following is a specification.

The object of my invention is to devise means for retaining in position the band or matrix used to form the outer wall of a cavity in the side of a tooth when putting in a filling; and it consists, essentially, of two holders pivoted by ball-and-socket joints on the inner ends of a pair of T-levers, which are centrally pivoted together and are provided between their outer ends with a spring,

means for locking the levers to cause them to rigidly hold the holders from spreading apart after being adjusted to the matrix, substantially as hereinafter more specifically described and then definitely claimed.

Figure 1 is a plan View of my improved matrix-retainer, full size. Fig. 2 is an enlarged perspective detail of. the holders, parts being shown separated. Fig. 3 is an enlarged perspective front view of one of the holders. Fig. 4 is an enlarged perspective detail of the means employed for locking the levers, the parts being shown separated. Fig. 5 is an enlarged cross-section through the sleeve an d expansion-plug of the look.

In the drawings like letters of reference indicate corresponding parts in the different figures.

Referring particularly to Fig. 1, A A are a pair of substantially T-shaped levers. The lugs a a, forming the stems of the T, are pivoted together at b. The inner end of each lever has a holder B, pivoted thereto by means of a ball-and-socket joint, the ball 0 being connected by a short stem with the end of the lever and the socket being formed partly in the holder B andpartly in the cap 0, secured thereto by screws or in any other suitable manner. The stems of the balls are connected to the ends of the levers by being soldered or shrunk into holes formed at their ends. Each holder has its face formed with two concave curves meeting in a central cusp. By reference to Fig. 3 it will be seen that the lower point of the cusp projects somewhat more than the upper point. I find this construction very advantageous, as while most teeth are somewhat bell-shaped, so that the holders fit best with the most extended point of the cusp lowermost, still others are best fitted when the most extended point of the cusp is uppermost. As the ball-andsocket joints permit the holders to be easily reversed, the latter may be easily fitted to suit the requirements of either type of teeth. It will be noticed also that the faces of the holders are slightly concave in a vertical section to enable them to fit closely the vertical curves of the teeth with which they may be engaged. At the outer end of one of the leversI hinge a nut D, through which is screwed an expanding screw E. This expandingscrew also screws within the upper end of the expansion-plug F, which is provided with a bore tapered toward the lower end of the split portion of the plug. (See Figs. 4 and 5.) This expansion-pin g fits within the sleeve Gr,WlllGll has a short spindle d formed thereon, extending through the end of the lever A. On the end of this spindle a milled head E maybe secured detachably or otherwise for convenience in handling the instrument. A fiangefis preferably formed on the expansion-plug F, bearing against the nut D, hinged on one of the lovers A. A similar flange g is formed on the sleeve G, bearing against the other lever A. Between these flanges is located a compression coil-spring H, which tends normally to expand the outer ends of the lovers, and thus cause the holders to firmly grip the tooth with which they are engaged, as shown in Fig. 1. In this figure a matrix 71 is shown in position to form the outer wall of a cavity in a tooth. This matrix is retained in position by the pressure of the two holders B, which are forced between the two teeth by the pressure of the coil-spring H. If it be desired to give additional security, by turning the milled head i of the expansion-screw E the expansion-plug F may be expanded within the sleeve G, causing the two to lock together in ing-screw willturn both plug and sleeve, and the screw turning in the nut D will put a positive strain on the levers, and thus relieve the spring of the responsibility of holding the matrix in position. While I prefer to hinge the nut D to the end of the lever A, yet this construction is not absolutely essential, as by making the threads therein a little slack for the screw E sufficient play may be given to allow the screw to adjust itself to the varying positions of the nut due to the opening and closing of the levers.

While I have described my invention in detail, I desire it to be understood that I do not wish to be confined to the exact construction described, as many variations in detail might be made without departing from the spirit of my invention.

What I claim as my invention is- 1. In a dental matrix-retainer a pair of levers pivoted together, in combination with a pair of holders one pivoted at the inner end of each lever by a ball-and-socket joint; and a spring connecting the levers and normally tending to force the holders toward one another, substantially as described.

2. In a dental matrix-retainer a pair of T- levers centrally pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever, and a compression coil-spring suitably arranged between the outer ends of the levers, substantially as described.

3. In a dental matrix-retainer a pair of le vers pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever by a ball-and-socket joint; a

spring connecting the levers and normally tending to force the holders toward one another; and an adjustable lock connecting the levers by means of which the levers may be locked to prevent the holders spreading after they have been adjusted to a matrix, substantially as described.

4. In a dental matrix-retainer a pair of T- levers centrally pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever; a compression coilspring suitably arranged between the outer ends of the levers; and an adjustable lock connecting the levers by means of which the levers may be locked to prevent the holders spreading after they have been adjusted to a matrix, substantially as described.

5. In a dental matrix-retainer a pair of levers provided with central lugs pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever; and a compression coil-spring suitably arranged between the outer ends of the levers, substantially as described.

6. In a dental matrix-retainer a pair of T- levers centrally pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever; a sleeve connected with the outer end of one lever; an expansionplug with a tapered bore engaging the outer end of the other lever and entering the aforesaid sleeve; and an expanding-screw passing through the end of the last-mentioned lever and screwed into the end of the plug, substantially as described.

7. In a dental matrix-retainer a pair of T- levers centrally pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever; a sleeve connected with the outer end of one lever; an expansionplug with a tapered bore engaging the outer end of the other lever and entering the aforesaid sleeve; an expanding-screw passing through the end of the last-mentioned lever and screwed into the end of the plug and a compression coil spring surrounding the sleeve and plug engaging the ends of the levers, substantially as described.

8. In a dental matrix-retainer a pair of T- levers centrally pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever by a ball-and-socket joint; a sleeve connected with the outer end of one lever, an expansion-plug, with a ta pered bore engaging the outer end of the other lever and entering the aforesaid sleeve; an

moved to any desired position, substantially as described.

10. In a dental matrix-retainer a pair of T- levers centrally pivoted together, in combination with a pair of holders, one pivoted at the inner end of each lever; a sleeve connected with the outer end of one lever; a nut hinged to the outer end of the other lever; an expansion-plug with a tapered bore entering the aforesaid sleeve, and an expanding-screw threaded to screw through the nut and into the end of the plug, substantially as described.

Brantford, August 30, 1902.

JOHN MILLS.

In presence of J ESSIE WEDLAKE, EDNA LEDDELL.

ICO 

